So got the H115i plat. but due to clearance problem from the ram (Corsair Vengeance RGB PRO) i can not mount it in the top (fractal R6).
So I have it mountet to the front with fans pulling air in from the front..
Would a fan at the buttom or 2x120mm fans at the top as intake help with cooling air for none cpu parts, or will the air coming through the radiator be enough.

So got the H115i plat. but due to clearance problem from the ram (Corsair Vengeance RGB PRO) i can not mount it in the top (fractal R6).
So I have it mountet to the front with fans pulling air in from the front..
Would a fan at the buttom or 2x120mm fans at the top as intake help with cooling air for none cpu parts, or will the air coming through the radiator be enough.

More airflow is never a bad thing. I would throw one there as it'll help cool an M2 drive if it's in a similar area at the bottom as mine are, plus over pressure inside the case isn't a bad thing, keeps dust and stuff from sneaking in cracks bypassing the filters. Maybe not 100% but a lot better than without.

So got the H115i plat. but due to clearance problem from the ram (Corsair Vengeance RGB PRO) i can not mount it in the top (fractal R6).
So I have it mountet to the front with fans pulling air in from the front..
Would a fan at the buttom or 2x120mm fans at the top as intake help with cooling air for none cpu parts, or will the air coming through the radiator be enough.

Use fan profiles to keep the speed low at idle and slowly ramp up the speeds as the component temperatures rise. Overall, the case is remarkably quiet given the number of fans that I have... OTT !

The Corsair ML 140mm twin-packs are great VFM on Amazon. I could not fit two 140mm fans behind the PSU, however a 140mm + 120mm does fit. Note that in general, 140mm fans are quieter that 120mm fans and they can shift more air.

There’s no reason not to put a fan or two at the bottom if you can. Even at low to moderate speed it should help move the warmer radiator exhaust out of the top rather than letting it move into the central GPU area that creates enough heat. Are you passive exhaust at the top? It may not be necessary to add them and you can experiment with top vs bottom, but I would place my bet on bottom intake for the most efficient results.